scholarly journals Aerial Versus Aquatic Oxygen Consumption in Larvae of the Clawed Frog, Xenopus Laevis

1984 ◽  
Vol 108 (1) ◽  
pp. 231-245 ◽  
Author(s):  
MARTIN E. FEDER ◽  
RICHARD J. WASSERSUG
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Xenopus Laevis ◽  
Total Oxygen ◽  
Pumping Rate ◽  
Aerial Respiration ◽  
Aquatic Respiration ◽  
Normal Feeding ◽  
Hypoxic Water ◽  
Clawed Frog

Tadpoles of Xenopus laevis Daudin can extract oxygen from both air and water. When these larvae have access to air, aerial oxygen uptake averages 16.6% of total oxygen consumption in normoxic water, and increases to 100% of net oxygen consumption in hypoxic water. Neither anaerobiosis nor increased buccopharyngeal ventilation occur in response to hypoxia. If tadpoles are prevented from surfacing to breathe air, they can maintain normal oxygen consumption through aquatic respiration alone in normoxic water, but not in hypoxic water. Unlike air-breathing larvae, exclusively water-breathing larvae respond to aquatic hypoxia by increasing their buccal pumping rate and by accumulating lactate. Even though Xenopus larvae can survive without air for many days, aerial respiration is necessary for other functions: tolerance of hypoxia, normal feeding, locomotion and buoyancy regulation.

scholarly journals Functional conflicts between feeding and gas exchange in suspension-feeding tadpoles, Xenopus laevis

1984 ◽  
Vol 110 (1) ◽  
pp. 91-98 ◽  
Author(s):  
M. E. Feder ◽  
D. B. Seale ◽  
M. E. Boraas ◽  
R. J. Wassersug ◽  
A. G. Gibbs
Keyword(s):  
Oxygen Consumption ◽  
Gas Exchange ◽  
Xenopus Laevis ◽  
Suspension Feeding ◽  
Air Breathing ◽  
Aerial Respiration ◽  
Metabolic Requirement ◽  
Rate Of Oxygen Consumption ◽  
Food Particles ◽  
Hypoxic Water

Air-breathing tadpoles of Xenopus laevis (Amphibia: Anura) use buccopharyngeal surfaces for both gas exchange and capture of food particles in the water. In dense food suspensions, tadpoles decrease ventilation of the buccopharynx and increase air breathing. The lung ventilatory frequency is elevated even though the rate of oxygen consumption is at or below resting levels, suggesting that the lung hyperventilation reflects compensation for decreased buccopharyngeal respiration rather than an increased metabolic requirement. If tadpoles in hypoxic water are prevented from breathing air, they increase buccopharyngeal respiration at the expense of feeding. Aerial respiration evidently permits the buccopharyngeal surfaces to be used primarily for food entrapment.

scholarly journals Developmental changes in oxygen consumption regulation in larvae of the South African clawed frog Xenopus laevis

1995 ◽  
Vol 198 (12) ◽  
pp. 2465-2475 ◽  
Author(s):  
D Hastings ◽  
W Burggren
Keyword(s):  
Oxygen Consumption ◽  
Lactic Acid ◽  
Xenopus Laevis ◽  
South African ◽  
Acute Hypoxia ◽  
Lactate Concentration ◽  
Aerobic Metabolism ◽  
Whole Body ◽  
Lactate Levels ◽  
Clawed Frog

Well-developed larval Xenopus laevis (NF stages 58­66) are oxygen regulators, at least during mild hypoxia. When and how they change from oxygen conformers (the presumed condition of the fertilized egg) to oxygen regulators is unknown. Also unknown is how anaerobic metabolic capabilities change during development, especially in response to acute hypoxia, and to what extent, if any, anaerobiosis is used to supplement aerobic metabolism. Consequently, we have investigated resting rates of oxygen consumption (M.O2) and concentrations of whole-body lactate (lactic acid) during development in normoxia and in response to acute hypoxia in Xenopus laevis. M.O2 increased in an episodic, non-linear fashion during development. Resting, normoxic M.O2 increased about tenfold (to approximately 0.20 µmol g-1 h-1) between NF stages 1­39 and 40­44, and then another tenfold between NF stages 45­48 and 49­51 (to approximately 2.0 µmol g-1 h-1), remaining at about 2 µmol g-1 h-1 for the remainder of larval development. M.O2 reached its highest level in newly metamorphosed frogs (nearly 4 µmol g-1 h-1), before decreasing to about 1.0 µmol g-1 h-1 in large adults. X. laevis embryos and larvae up to NF stage 54­57 were oxygen conformers when exposed to variable levels of acute hypoxia. The only exception was NF stage 45­48 (external gills present yet body mass still very small), which showed some capability of oxygen regulation. All larvae older than stage 54­57 and adults were oxygen regulators and had the lowest values of Pcrit (the oxygen partial pressure at which M.O2 begins to decline). Whole-body lactate concentration in normoxia was about 1 µmol g-1 for all larval groups, rising to about 12 µmol g-1 in adults. Concentrations of lactic acid in NF stages 1­51 were unaffected by even severe ambient hypoxia. However, whole-body lactate levels in NF stages 52­66 increased in response to severe hypoxia, indicating that some anaerobic metabolism was being used to supplement diminishing aerobic metabolism. The largest increases in concentration of lactate occurred in late larvae and adults.

Cardio-respiratory ontogeny during chronic carbon monoxide exposure in the clawed frog Xenopus laevis.

1998 ◽  
Vol 201 (9) ◽  
pp. 1461-1472 ◽  
Author(s):  
P R Territo ◽  
W W Burggren
Keyword(s):  
Oxygen Consumption ◽  
Xenopus Laevis ◽  
Lactate Concentration ◽  
Respiratory Physiology ◽  
Whole Body ◽  
O2 Transport ◽  
Rate Of Oxygen Consumption ◽  
Stage 1 ◽  
Clawed Frog ◽  
Individual Mass

The present study investigates the ontogeny of cardio-respiratory physiology in Xenopus laevis where O2 transport is obstructed. Animals were raised from eggs (NF stage 1) to metamorphic climax (NF stage 63), while maintained either in air or in chronic 2 kPa CO, which functionally ablates O2 transport by hemoglobin (Hb). Whole-animal rate of oxygen consumption (.MO2), whole-body lactate concentration, individual mass, heart rate (fh) and stroke volume (Vs) were measured. Additionally, cardiac output (.Q) and the ratio of the rate of oxygen consumption to the total rate at which oxygen is transported in the blood (.MO2/.QO2) were calculated to determine limitations imparted when O2 transport is impaired. Our data on early development suggest that the onset of convective blood flow occurs prior to the absolute need for convection to supplement diffusive transport. Values for .MO2, whole-body lactate concentration, mass and fh did not differ significantly between controls and CO-exposed animals. However, CO-exposed animals showed a significant (P<0.05) increase in Vs, .MO2/.QO2 and .Q compared with controls. These results indicate that limiting blood O2 transport is not deleterious to metabolism and development as a whole and that convective oxygen transport via Hb is not essential for normal cardiovascular or respiratory function during larval development.

Hourly and total oxygen consumption by ova of Atlantic salmon, Salmo salar L., during embryogenesis, at two temperatures and three levels of dissolved oxygen

1979 ◽  
Vol 57 (6) ◽  
pp. 1196-1200 ◽  
Author(s):  
T. Hamor ◽  
E. T. Garside
Keyword(s):  
Oxygen Consumption ◽  
Atlantic Salmon ◽  
Oxygen Uptake ◽  
Dissolved Oxygen ◽  
Salmo Salar ◽  
Developmental Time ◽  
Total Oxygen ◽  
Weighted Mean ◽  
Atlantic Salmon Salmo Salar ◽  
Two Temperatures

Weighted mean hourly rates of oxygen consumption in embryonated ova of Atlantic salmon, Salmo salar L., during embryogenesis, were reduced significantly by levels of dissolved oxygen below air saturation and by a temperature of 5 °C, relative to those for ova incubated at 10 °C. Total oxygen consumption during embryogenesis also was reduced significantly by the lower levels of dissolved oxygen, but not by temperature. The decrease in the pace of embryogenesis in the lots of ova at 5 °C extended the developmental time so that the lower rate of oxygen uptake was offset. Thus, within each level of dissolved oxygen there was no appreciable difference in the products of time units and units of oxygen uptake. At 5 °C, 100% air saturation, mean hourly uptake was 0.0141 mg O2/ovum, and total uptake was 28.153 mg O2/ovum. At 10 °C, 100% air saturation, these values were 0.0270 mg O2/ovum, and 27.974 mg O2/ovum, respectively. Values for ova incubated at 50 and 30% air saturation were correspondingly lower.

Influence of Endogenous OUR Determination on the KLa$${K_L}a$$, Exogenous OUR, Total Oxygen Consumption and Heterotrophic Yield in a Completely Mixed Batch Reactor

2014 ◽  
Vol 12 (2) ◽  
pp. 695-704 ◽  
Author(s):  
R. Zamouche-Zerdazi ◽  
M. Bencheikh Lehocine ◽  
A.-H. Meniai
Keyword(s):  
Wastewater Treatment ◽  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Uptake Rate ◽  
Oxygen Uptake Rate ◽  
Batch Reactor ◽  
Total Oxygen ◽  
Biomass Activity ◽  
Biological Reaction ◽  
Global Nature

Abstract In wastewater treatment, waste removal and biomass activity are important processes which need to be monitored for a good process control. The difficulties in the interpretation of the total COD, BOD and VSS measurements encouraged the development of respirometric methods for assessing the kinetic constants. Respirometry is an important technique in assessing biological reaction in wastewater treatment. $${K_L}a$$, depends on endogenous oxygen uptake rate (OURend), is a key constant in evaluating respirogram-specific parameters. Generally, OURend is assumed constant in the dissolved oxygen equations. However, it is not the case. Consequently, this paper deals with the influence of OURend calculations region on $${K_L}a$$ determination, exogenous oxygen uptake rate (OURexo), total oxygen consumption and heterotrophic yield (YH). It was shown that the value of OURend and $${K_L}a$$ varied considerably, a maximum of 56%, depending on where to consider Cfin, on the oxygen concentration variation curve. Even though, the variation on OURend and $${K_L}a$$ is important its influence on Yo/x and YH is attenuated to 7.5% and 6%, respectively. This may be due to the local nature of the first parameters (OURend and $${K_L}a$$) and the global nature of the later ones. Moreover, this can be seen through the variation of the calculated amount of oxygen consumed (QThete) which is of the order 7.6%.

Respiration of the amphibious fishes Periophthalmus cantonensis and Boleophthalmus chinensis in water and on land

1976 ◽  
Vol 65 (1) ◽  
pp. 97-107 ◽  
Author(s):  
S. O. Tamura ◽  
H. Morii ◽  
M. Yuzuriha
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Terrestrial Habitat ◽  
Total Oxygen ◽  
Total Uptake ◽  
Amphibious Fishes

1. The routine oxygen consumption by Periophthalmus cantonensis and Boleophthalmus chinensis in water increased geometrically, whereas that in air increased logarithmically with temperature. At temperatures of more than 20 degrees C the oxygen uptake of both species was greater in water than in air. 2. When the fishes were able freely to select either an aquatic or terrestrial habitat, the total oxygen consumption of Periophthalmus and Boleophthalmus was 236 and 110 ml/kg, h at 20 degrees C respectively; 66% (Periophthalmus) and 70% (Boleophthalmus) of the total uptake was from water, and 34 and 30% of the total uptake was from air at 20 +/− 1 degrees C. 3. Oxygen uptake of fish limited to aquatic or terrestial life was less than when they could freely select their habitat; for Periophthalmus, uptake was reduced to 83% when confined in water and to 50% in air, and for Bolephthalmus, to 65% in water and to 43% in air. 4. The proportion of oxygen uptake by the gill in water was 52% for Periophthalmus and 59% for Boleophthalmus; in air the corresponding figures were 27 and 52%. 5. The proportions of oxygen uptake via the skin in water was 48% for Periophthalmus and 36% for Boleophthalmus; in air the corresponding figures were 76 and 43%. 6. It is concluded that, on land, Periophthalmus relies mainly on its skin and Boleophthalmus relies mainly on its gills.

scholarly journals Studies on the Queensland lungfish, Neoceratodus forsteri (Krefft). 3. Aerial respiration in relation to habits.

1965 ◽  
Vol 13 (3) ◽  
pp. 413 ◽  
Author(s):  
GC Grigg
Keyword(s):  
Oxygen Consumption ◽  
Alternative Hypothesis ◽  
Juvenile Fish ◽  
Current Theory ◽  
Field Observations ◽  
Respiratory Organ ◽  
Pumping Rate ◽  
Air Breathing ◽  
Aerial Respiration ◽  
Active Fish

Field observations made on the Mary and Burnett rivers in Queensland show that seasonal stagnancy and deoxygenation are unlikely to be factors accounting for the air-breathing habit in Neoceratodus, as current theory suggests. An alternative hypothesis that the lung is an accessory respiratory organ during active periods, was suggested by current work which showed that Neoceratodus is more active nocturnally and surfaces to take air more often at night. Respirometry studies on juvenile fish confirmed this, for the oxygen consumption of forcibly active fish prevented from surfacing while in the respirometer, was consistently lower than that of fish allowed to surface. At 25�C, active fish allowed to surface had an oxygen consumption of 0.07 ml g-l hr-l, derived from branchial respiration at a rate of 67 beats/min supplemented by use of the lung. When prevented from surfacing however the oxygen consumption fell to approximately 0.05 ml g-l hr-1, derived from gills alone, but with a branchial pumping rate of 80 beats/min. This correlation of oxygen consumption with branchial pumping emphasizes the limit placed on the fish by its gills, whereas the higher oxygen consumption exhibited by active fish allowed to surface indicates the value of the lung as an accessory respiratory organ, allowing more vigorous reaction to a stimulus than would be possible with gills only.

scholarly journals The effects of aquatic oxygen concentration, body size and respiratory behaviour on the stamina of obligate aquatic (Bufo americanus) and facultative air-breathing (Xenopus laevis and Rana berlandieri) anuran larvae

1983 ◽  
Vol 105 (1) ◽  
pp. 173-190
Author(s):  
R. J. Wassersug ◽  
M. E. Feder
Keyword(s):  
Body Size ◽  
Xenopus Laevis ◽  
Oxygen Concentration ◽  
Interspecific Variation ◽  
Bufo Americanus ◽  
Aquatic Respiration ◽  
Rana Berlandieri ◽  
Hypoxic Water ◽  
Large Animals ◽  
The Relationship

Larvae of the anurans Rana berlandieri and Xenopus laevis have lungs and can breathe air as well as irrigate buccal and pharyngeal surfaces for aquatic respiration. Larvae of Bufo americanus lack lungs until just before metamorphosis and are obligately aquatic. We examined the relationship between the locomotor stamina (time to fatigue), aquatic oxygen concentration, body size, and respiratory behaviour of swimming larvae of these species, with the following results: Stamina is size-dependent in all three species. Aquatic hypoxia reduces stamina in larvae of all three species, but most conspicuously in Bufo. Breathing air increases stamina in Rana larvae, especially in large animals and under aquatic hypoxia. In contrast to Rana larvae, Xenopus larvae swimming in normoxic water undergo a reduction in stamina when allowed to breathe air. In hypoxic water, aerial respiration moderates the reduction in stamina seen in Xenopus larvae. Branchial irrigation is associated with increased stamina in Xenopus, and is increased under hypoxia and at high swimming velocities. Respiratory demand, buoyancy and the drag associated with branchial irrigation all affect respiratory behaviour in Xenopus larvae. The great amount of interspecific variation in the relationship between respiratory behaviour and stamina reveals the importance of measuring performance directly when attempting to interpret the functional significance of respiratory structures and behaviour.

Thyroid hormones and behavioral thermoregulation by Xenopus laevis: differential effects of thyroxine and triiodothyronine

1986 ◽  
Vol 64 (5) ◽  
pp. 1076-1079 ◽  
Author(s):  
R. Keith Dupré ◽  
John J. Just ◽  
J. P. Ritchart
Keyword(s):  
Oxygen Consumption ◽  
Xenopus Laevis ◽  
Thyroid Hormones ◽  
Hormone Treatment ◽  
Behavioral Thermoregulation ◽  
Temperature Selection ◽  
African Clawed Frog ◽  
Secondary Result ◽  
Clawed Frog ◽  
Selection Of

The effects of 1 μM 2,4-dinitrophenol, 2.5 × 10−8 M thyroxine, and 2.5 × 10−8 M triiodothyronine on the oxygen consumption and behavioral temperature selection of the African clawed frog, Xenopus laevis, were examined to test the hypothesis that the selection of lower temperatures by thyroxine-treated ectotherms is a secondary result of the calorigenic effect of the hormone. Treatment with the metabolic poison 2, 4-dinitrophenol produced a significant increase in oxygen consumption but had no significant influence on temperature selection by the clawed frogs, suggesting that an increase in oxygen consumption in itself does not induce the selection of lower temperatures by ectotherms. Furthermore, neither thyroxine nor triiodothyronine affected the standard oxygen consumption of the clawed frogs at 23 °C but both significantly affected behavioral temperature selection. Treatment with thyroxine resulted in the selection of significantly lower temperatures than untreated controls. Conversely, treatment with triiodothyronine resulted in the selection of significantly warmer temperatures. These data suggest that thyroid hormones do not affect behavioral thermoregulation of ectotherms via an indirect calorigenic effect but may act directly on the neural regions involved with the sensation and (or) integration of thermal information. These data further suggest independent roles for thyroxine and triiodothyronine in the modulation of temperature selection by anuran amphibians.

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

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